Wasia-Biyadh-Aruma Aquifer System (South)

Tawila-Mahra/Cretaceous Sands

Executive Summary

The Wasia-Biyadh Sandstones merge with the Aruma in the southern areas of Saudi Arabia to constitute the so-called Cretaceous Sands. These sandstones extend across the Rub' al Khali Depression into Yemen where stratigraphically correlatable sandstones exist (the so-called Tawila-Mahra Group), thus forming a transboundary aquifer system denoted here as the Wasia-Biyadh-Aruma Aquifer System (South).

The maximum extraction potential from this aquifer system is estimated at around 500 BCM, making this one of the most promising groundwater reservoirs in the Arabian Peninsula. The aquifer system is hardly used at present due to the remote and harsh nature of the sparsely populated desert environment. Extraction only takes place in the area around the Sharurah/Al Abr border posts, where the sandstones appear at or near the surface, and nomadic populations use freshwater from shallow wells for drinking water supply. The presence of exploratory wells in the sandstones south of the delineated area indicates that freshwater is also found at depth.

This large reservoir of fresh groundwater is an important resource for the economic development of the Sharurah/Al Abr area in the future. It may also prove to be a source of water for more distant but rapidly developing urban areas that face growing water shortage such as Najran in Saudi Arabia and Sa'dah in Yemen.

The Bir Ali Crater with the Gulf of Aden in the background, Yemen, 2009. Source: Email4Mobile.

Between Mukalla and Bir Ali, Yemen, 2000. Source: Kebnekaise.

Wadi Doan, Yemen, 2000. Source: Kebnekaise.

Mukalla, Yemen, 2000. Source: Kebnekaise.

Basin Facts

Riparian Countries

Saudi Arabia, Yemen

Alternative Names

Cretaceous Sands, Mahra Group, Tawila Group

Renewability

Very low (0-2 mm/yr)

Hydraulic Linkage with Surface Water

Weak to medium

Rock Type

Mixed

Aquifer Type

West: ConfinedEast: Unconfined

Extent

~157,000 km2

Age

Mesozoic (Cretaceous)

Lithology

Predominantly sandstones with some marls and siltstones

Thickness

100-200 m

Average Annual Abstraction

Unknown, but very limited

Storage

~500 BCM

Water Quality

Fresh (400-800 mg/L TDS)

Water Use

Water supply for desert nomads and the Sharurah/Al Abr border posts

Agreements

--

Sustainability

--

The Inventory of Shared Water Resources in Western Asia is a comprehensive report published by the United Nations Economic and Social Commission for Western Asia (UN-ESCWA) and the German Federal Institute for Geosciences and Natural Resources (BGR), with financial support from the German Federal Ministry for Economic Cooperation and Development (BMZ).